The language of envelopes

The language of paper

Weights and measurements of paper

The German, Walter Porstmann proposed a standard norm for paper formats which was adopted in Germany in 1922 as DIN formats (Deutsche Industrie Norme) and which today is the standard international measurement (ISO 218). Based on the metric system, he started from one square metre of paper, so that the successive divisions maintained the same proportion between the sides of the rectangle. Only one formula presents this relationship: